An organic light-emitting device is a device having a thin film which contains a fluorescent or phosphorescent organic compound and is interposed between electrodes. Electrons and holes (positive holes) are injected from the respective electrodes, whereby excitons of the fluorescent or phosphorescent compound are produced. The excitons radiate light upon return thereof to a ground state. Recent progress of an organic light-emitting device is remarkable, and the characteristics of the device enable a thin and light weight light-emitting device with a high luminance at a low applied voltage, a variety of emission wavelengths, and a high-speed responsibility. From this fact, it is suggested that the device have potential to find use in a wide variety of applications.
However, in the present circumstances, an optical output with a higher luminance or a higher conversion efficiency is needed. In addition, the organic light-emitting device still involves a large number of problems in terms of durability such as a change over time due to long-term use and degradation due to an atmospheric gas containing oxygen, moisture or the like. Further, when the application of the device to a full-color display or the like is taken into consideration, the emission of blue, green, or red light with good color purity is needed. However, these problems have not been sufficiently solved yet.
Meanwhile, a benzofluoranthene compound has been proposed as a blue-light-emitting material. Organic light-emitting devices using a benzofluoranthene compound as a light-emitting material have been disclosed in Japanese Patent Application Laid-Open Nos. H10-294179, 2002-69044, 2003-26616, and 2005-68087. However, it is difficult to say that those organic light-emitting devices have sufficient life characteristics. In particular, when one attempts to apply those devices to a full-color display, the compound cannot be employed as a blue-light-emitting material which can satisfy demands for satisfactory emission efficiency, durability life, and color purity.